Opening/saving files slow when laptop is away from domain

I have a Win2K3 domain with about 25 desktop machines and 5 laptops.
When some the laptops are away from the domain opening and saving
local files takes several minutes. I've seen this problem before when
the computers have a network share mapped to a drive letter, but that
isn't the case here. I imagine that the machines are trying to resolve
something on the network and eventually timing out, but I don't know
what it is that they're looking for or how to stop it.

Any ideas?

Thanks,

--TWH